Usually process control systems are developed by a manufacturer, delivered to customers, installed in a technical system to be controlled and put into operation. The process control system consists in this case of hardware and software components which each implement at least one technical control function of the process control system. The sum of these functions provides the customers with a multiplicity of operating, observation and regulation options for the technical system.
Mostly the customer pays a price for the supply and if necessary the installation of the process control system, for example an agreed purchase price as a one-off payment, which includes the use of the process control system over its lifetime with all its functions, in which case the price given does not take into account to extent to which customers actually use the functions provided and/or how often and/or for what period specific functions are used. Furthermore customers normally receive a project planning system as part of the process control system, with which they can implement new technical control functions or can modify supplied control functions, so that the process control can be adapted during its years of operation at any time to the changing requirements of the technical system. This aspect too is not taken into account in the pricing of the process control system, Customers pay a—mostly very high—purchase price and can use the supplied components of the process control system practically as they wish, without greater or lesser use of the functions of the process control system being reflected in a subsequent payment or repayment of at least a part of the purchase price.
With a known process control system the customer thus mostly pays at the time of delivery the purchase price for the process control system, which includes a proportion of the price in each case for the hardware and the software supplied. So for the customer a greater financial investment is needed, at the latest by the time of delivery, to obtain an operable process control system with all hardware and software components.